A fresh tea bud and leaf is picked from the moment its flavour starts to shift and grow. While some of these improvements are helpful and will determine what type of tea the leaf will become, the product starts to lose some of its flavour once the processing is completed almost immediately. Teas are at their best the younger they are, as a very general rule of thumb. The longer they are left exposed to heat and air, the more they tend to lose their vibrancy and fresh flavour. look at this site
A good online tea shop will always be able to, at the very least, let you know the year it was harvested, if not the exact date of harvest and production, when buying whole leaf teas. (I.E. Spring 2011) This article was written to let you know what you should be searching for with regard to the age of the tea style when buying tea gifts online.
The Green Teas
Green teas and mildly oxidised Oolongs have a shelf life of just around 6 months to 1 year, such as the Taiwanese ‘Bao Zhong’. Although you will still be able to make tea from these leaves after this time, its flavour will decrease dramatically from how the master blender intended it to taste. This is the youngest and freshest tasting and should be drank this way as such. Any online tea shop that sells green tea much longer than 1 year after harvest has obviously bought too much or doesn’t know much about tea! Buy only green teas that are 1 year or less old.
The Oolong Teas
Semi oxidised Oolong teas have a shelf life of about 1 to 2 years, which is slightly longer. However, after some time , usually after 1 year, some traditional Chinese Oolongs that have been roasted actually strengthen and soften, but a good online retailer should be able to advise you on this. However, there are aged Oolongs that provide an exception. These teas may have been aged for up to 3 to 25 years and will be re-roasted periodically to control the moisture content. They should be treated as the only exception to the law of 1 to 2 years.
Around Black Teas
Black teas are oxidised completely, hence their dark hue. This oxidisation means that all teas have the longest shelf life and will be good to drink for anywhere from 1 to 3 years. However, they will start losing some of their flavour properly stored during this period of time-in a cool but not cold setting, which is neither too dry or damp, and kept out of direct sunlight-these leaves will retail much of their flavour for the entire period of that time.